Known are energy storage systems and portable (or auxiliary) power systems for general home use or, on a larger scale, for commercial buildings, for example, hospitals. Also, auxiliary power systems may be used to provide power for many types of equipment, such as lighting, sound systems, amusement park rides, on site machinery or tools, or mobile emergency systems. The power system may include an engine and generator combination (also referred to as a generator set), which may include a diesel or gasoline engine driving a generator which produces a voltage output.
Other power systems may include the use of photovoltaics used directly as a power source, and which may also be fed back to a local power grid, for example, a utility grid. Another power system may include a diesel generator set, or engine generator set. The generator provides alternating current (AC) power to a junction box or bus bar to power a load source. Such systems require running the engine at a constant engine speed using a regulator or governor, and a generator voltage regulator. The system typically requires a transfer switch to disconnect the load from the utility power source, and connect the generator to the load when there is a power failure. Further, typically generators require the engine to run at a predetermined speed to provide power at the proper frequency. When the engine is not running at optimum speed for a given load, the engine may have very poor efficiency.
For example, typical synchronous generator sets must operate the engine at a fixed speed (typically 1800 or 3600 (revolutions per minute) RPM) in order to produce a required 60 Hz frequency output voltage. When there is low output load, or no output load, a large portion of fuel consumption is required to maintain a moderate to high engine speed and thus makes the system very inefficient. Additionally, another shortcoming of known generator sets occurs when the power system experiences a large instantaneous load such as from a large motor or heating element, the engine cannot respond instantly, resulting in a momentary droop in frequency and possibly also in voltage, depending on the voltage regulation system.
Therefore, a need exists for a system and method for providing power in a portable electrical generator set which is more efficient than existing systems.